Editor's note Sept. 27: The Senate has now invited Facebook and Google to testify at an upcoming hearing examining Russia's use of social media in last year's election, according to a person familiar with the matter. Twitter didn't immediately respond to a request for comment about whether it too has been asked to testify. The Hill newspaper earlier reported the development. The original story about the hearing, from Sept. 19, is below.

Facebook representatives are expected to be called to testify at a Senate hearing examining Russia's use of social media to influence last year's US election.

It wasn't immediately clear who would be invited to testify or what issues will be discussed, Richard Burr, who chairs the Senate Intelligence Committee, told reporters in Washington on Tuesday. Twitter and other social media companies may also be invited, Burr said, according to Bloomberg.

"We're in agreement on a Facebook public hearing," the North Carolina Republican said. "It's just a question of when and potentially the scope."

Details on the hearing emerge as Russian operatives continue to use social media to try to stoke divisiveness in the US, the New York Times reported late Wednesday. Researchers at the Alliance for Securing Democracy, found that 600 Twitter accounts it had been tracking for weeks had been used to push opposing messages in the debate last weekend over whether NFL players should stand or kneel during pregame performances of the national anthem.

Facebook has also reportedly sent special counsel Robert Mueller records about Russian-linked ads placed on its service during the 2016 election campaign. Mueller and a team of investigators are conducting the high-profile Russia investigation, which has raised issues concerning President Donald Trump's election last year, the involvement of his children and the actions of his staff.

Less than a week ago, Facebook revealed it had sold $100,000 worth of ads to inauthentic accounts likely linked to Russia during the US presidential election. Russian operatives also reportedly used Facebook Events to remotely organize political protests in the US, including a 2016 anti-immigration rally in Idaho.

Facebook didn't immediately respond to a request for comment.

CNET's Terry Collins and Richard Nieva contributed to this story.

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